The third possibility is not just to bind up the wounds of the victims beneath the wheel but to seize the wheel itself [(The Bonhoeffer reader, ed. Green and DeJonge (Fortress Press, 2013), 374)].

The third possibility is not just to bandage the victims under the wheel, but to jam a spoke in the wheel itself [(Testament to freedom: the essential writings of Dietrich Bonhoeffer, ed. Kelly & Nelson (HarperSanFrancisco, 1990), 139)].

The third possibility is not just to bandage the victims under the wheel, but to put a spoke in the wheel itself [(Dietrich Bonhoeffer: witness to Jesus Christ, ed. De Gruchy (Collins, 1988), 127; No rusty swords: letters, lectures and notes 1928-1936, from the collected works of Dietrich Bonhoeffer, volume 1, ed. Robertson, trans. Robertson & Bowden (New York: Harper & Row, 1965), 225)].

Dietrich Bonhoeffer Works 12, 365n12: "This is the famous phrase 'dem Rad selbst in die Speichen zu fallen,' often translated as 'to fall within the spokes of the wheel.' As German editor Ernst-Albert Scharffenorth notes, however, Bonhoeffer and his readers would have understood this as the act of detaching a cart or wagon from the horse pulling it. In any case, the meaning clearly is to bring the apparatus of the unjust and illegitimate state to a halt. 'To seize the wheel itself' is the English phrase; for this reason we use that translation here." (It should be noted, however, that the essay should be read in its entirety, and Bonhoeffer's position on role of the Church in speaking truth to the State carefully noted, as the latter is not—was not yet at that point in time, at least—what those who bandy these words about in a sub-Lutheran American context tend to make of it.)

The second appears to me to have been back-translated (?) into German as

and so forth (a potential indication of inauthenticity), but has (so far as I know) yet to be located in the works of Bonhoeffer, and did not—as of 1 March 2016—occur here. See the "Master index of subjects" at p. 601 of Dietrich Bonhoeffer Works 16 (Indexes and supplementary materials), where the two German terms for "silence" in Bonhoeffer are given as Rühe and Schweigen; and where vol. 14* (for Rühe) and vols. 3*, 4*, 14*, and 16* (for Schweigen) bear an asterisk "indicat[ing] that the term in question was a significantly indexed entry in the German index volume (DBW 17), but was either not indexed at all in the respective DBWE[nglish] volume or was indexed under a different entry." (I have checked the references in vols. 3 (whose index actually lacks an entry labelled "silence"), 7, and 8 (for Rühe) and vols. 6, 7, 8, 10, and 12 (for Schweigen) of the English edition. I have also run a varied series of Google and full-text databases searches, but without any success so far. Though he was by no means the first to have thus "quoted" Bonhoeffer without referencing a source (James Cone and others were doing so long before him), Eric Metaxas seems to have been the one greatly to popularize the "quotation". Though Google Books offers a searchable "Preview" version of the Metaxas biography here, I have not been able to get it to return an occurrence of the "quotation" anywhere other than on the dust jacket, where, of course, the source is not given.) I would appreciate hearing from anyone who can prove my suspicions unfounded, but on 24 July 2016 Dr. Clifford J. Green, Bonhoeffer Chair Scholar, Union Theological Seminary and Executive Director, Dietrich Bonhoeffer Works, graciously responded to an inquiry of mine by confirming that he and his colleagues had (by that point at least) never been able to trace "Silence in the face of evil" back to Bonhoeffer himself. See now Michael P. DeJonge, Bonhoeffer on resistance: The word against the wheel (Oxford: Oxford University Press, 2018), which, though it contains several references to the first, genuine half of the quote on "jam[ming] a spoke into the wheel [of injustice] itself," contains none of the following English words and phrases: silence (!), guiltless, "not to speak," "not to act" (not schuldlos or Handeln either). (I haven't read this, though; only searched it.)